The present invention relates generally to surgical instruments and more specifically to surgical clips used in surgical clip appliers for ligating blood vessels and other tubular ducts or tissue.
In surgical procedures, it is frequently necessary to ligate ducts, such as blood vessels, or other severed tissue. For this purpose, it is well-known to use surgical clip appliers, such as that described in U.S. Pat. No. 3,439,522, to apply surgical clips to a duct or tissue to be ligated. Such clip appliers typically have a scissor-like construction, with a pair of movable handles which are grasped by the surgeon, and a pair of movable jaws opposite the handles into which a surgical clip is placed. Surgical clips usually have a pair of connected legs to form a U or V shape. When the handles are closed, the jaws close the legs of the clip together on the vessel or other tissue to be ligated.
In some surgical procedures, it is desirable to use a clip applier which is configured to allow tissue ligation in inaccessible areas of the surgical site. To address this need, a number of surgical clip appliers have been developed with the jaws extended a distance from the handles, or with the jaws oriented at various angles. Examples are described in U.S. Pat. Nos. 3,777,538, and 4,440,170.
Other known clip appliers, such as that described in U.S. Pat. No. 4,616,650, provide for retaining multiple clips in the applier and feeding the clips toward the distal end of the applier, thereby permitting the surgeon to apply multiple clips at various places in the surgical site without removing the clip applier from the site to place another clip in the jaws. In some of these known devices, the clip applier is designed to accommodate an interchangeable cartridge containing multiple clips. An example is seen in U.S. Pat. No. 3,675,688.
Other clip appliers have been developed for use in laparoscopic surgical procedures. Laparoscopic procedures usually involve distending the abdominal cavity away from the underlying organs to improve access and visibility, using gas insufflation or a mechanical distension technique. Several small incisions are made in the abdomen through which are inserted trocar sleeves--plastic tubes designed to provide a sealed entryway into the abdominal cavity. Surgery is performed using long-handled instruments inserted through the trocar sleeves, with a lens connected to a video monitor providing visibility of the abdominal cavity.
The parent to this application describes a clip applier having particular usefulness in laparoscopic surgery. The clip applier includes an elongated shaft mounted to a handle, with a movable belt disposed in the shaft having a plurality of retainers for holding clips. An anvil is mounted at the distal end of the shaft and a hammer is movable against the anvil by actuating a lever mounted to the handle. A unique feature of the clip applier is the feeding of the clips on the belt with the legs pointing distally, then rotating the clips so that the legs point laterally in the anvil. Also unique is the curved shape of the anvil and the distal end of the hammer, which form the legs of the clip in a curved and parallel configuration when the clip is closed. It has been found that this curved configuration results in improved gripping force on the tissue to which the clip is applied, and permits the amount of clip surface available for gripping tissue to be maximized relative to the size of the clip.
Various types of surgical clips have been developed for use in clip appliers like the forementioned. However, it has been found that known surgical clips suffer from certain disadvantages. First, known surgical clips are not suitable for use in a clip applier which closes clips in a curved shape, like that described in the parent to this application. Because known clips generally have two legs of the same length, if such clips are formed in a curve when closed, the tip of one leg (on the inside of the curve) will extend beyond the tip of the other leg (on the outside of the curve). This effectively reduces the amount of surface area of the clip available for gripping tissue, reducing its effectiveness.
Known surgical clips further suffer from undesirably low reliability in remaining properly secured to the desired tissue area. Several factors contribute to this problem, including the tendency of the clip legs to spread apart due to their inherent resiliency, as well as inadequate grip between the clip surfaces and the tissue to which the clip is applied.
In addition, known surgical clips have an undesirably small area of clip surface available for gripping tissue relative to the overall size of the clip. This is especially significant in laparoscopy, where the clip applier with clips retained therein must be inserted through a trocar sleeve of limited size. Such sleeves commonly have a diameter of 10 mm. A clip applier and clip must be designed to be inserted through such a sleeve, while at the same time maximizing the area of the gripping surface of the clip. If it is desired to use a clip applier for applying clips in a lateral, rather than distal direction, clip size is particularly limited, since the laterally-facing jaws for closing the clips must be small enough to fit through the trocar sleeve, thereby limiting the height of the clips. Known clips suitable for lateral application which are insertable through a 10 Mm trocar sleeve have incorporated geometries which have limited the surface area available for gripping.
For these and other reasons, a surgical clip is desired which can be closed in a curved configuration, and which has improved reliability in remaining secured to tissue. Preferably, the clip could be used in conjunction with a variety of clip appliers, including those with distally-facing jaws, those with laterally-facing jaws, those employing cartridges for holding multiple clips, and those having belt-type feed mechanisms. The surgical clip should have improved gripping surfaces as well as tighter closure between the legs to ensure security on the tissue to which the clip is applied. The clip should further provide a large area of gripping surface relative to the overall size of the clip.